调整五子棋难度级别为2~5

app/Services/GomokuAiService.php

@@ -40,10 +40,10 @@ class GomokuAiService
     public function think(array $board, int $aiLevel): array
     {
         return match ($aiLevel) {
-            1 => $this->thinkMinimax($board, 1),  // 简单：深度1
-            2 => $this->thinkMinimax($board, 2),  // 普通：深度2
-            3 => $this->thinkMinimax($board, 3),  // 困难：深度3
-            default => $this->thinkMinimax($board, 4),  // 专家：深度4
+            1 => $this->thinkMinimax($board, 2),  // 简单：深度2
+            2 => $this->thinkMinimax($board, 3),  // 普通：深度3
+            3 => $this->thinkMinimax($board, 4),  // 困难：深度4
+            default => $this->thinkMinimax($board, 5),  // 专家：深度5
         };
     }